CAP TODAY Pathology/Laboratory Medicine/Laboratory Management
Collection and handling takeaways for cytopathology practice
Sinchita Roy-Chowdhuri, MD, PhD
August 2020—Cytopathologists are keenly aware of the need to collect adequate cytologic tissue not only to arrive at a diagnosis but also to provide sufficient material for predictive and prognostic markers. This is especially true in the realm of non-small cell lung cancer, where biomarker testing is routinely used for the clinical management of patients with advanced-stage disease. The list of clinically relevant biomarkers in NSCLC is expanding.
The most recent version of the National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology includes MET exon 14 skipping mutations and RET as therapeutic targets for advanced NSCLC, in addition to the well-established EGFR and BRAF mutations, ALK and ROS1 rearrangements, and PD-L1 expression.1 Testing modalities for these seven “must test” biomarkers is extensive, ranging from PCR-based methods for mutational analysis to fluorescence in situ hybridization assays to identify gene rearrangements, to immunohistochemistry for quantifying protein expression in tumor cells. Not surprisingly, small specimens collected by minimally invasive techniques, such as fine-needle aspiration and core needle biopsy, often fall short in meeting adequacy requirements for the myriad testing modalities for a growing list of biomarkers.2,3
The CAP has been at the forefront in leading laboratory practice by developing evidence-based practice guidelines that help direct clinicians and laboratories. To that end, the CAP recently published the guideline on collecting and handling thoracic small biopsy and cytology specimens for ancillary studies, which is aimed at providing direction to proceduralists and pathology laboratory personnel for the most optimal collection and handling of such specimens.4 The guideline was developed in collaboration with stakeholders from eight other professional medical societies: American College of Chest Physicians, American Society of Cytopathology, American Thoracic Society, Association for Molecular Pathology, Papanicolaou Society of Cytopathology, Pulmonary Pathology Society, Society of Interventional Radiology, and Society of Thoracic Radiology. A multidisciplinary expert panel, composed of cytopathologists, a cytotechnologist, molecular pathologists, pulmonary pathologists, interventional pulmonologists, interventional radiologists, and a research methodologist, with input from a separate advisory panel, worked through 4,256 peer-reviewed published studies that were identified in the systematic review to develop 16 guideline statements on the best practices for acquiring and handling thoracic small specimens for ancillary studies.
The guideline covers six main aspects of thoracic small specimen acquisition: endobronchial ultrasound-guided transbronchial procedures, transthoracic procedures, bronchoscopic procedures, pleural effusions: considerations for malignancy, considerations for ancillary studies during malignant investigations, and considerations for ancillary studies during nonmalignant investigations. It includes a range of ancillary studies, from those used for patients with lung cancer to those used in the diagnosis of infectious processes such as pulmonary and extra-pulmonary tuberculosis. While a detailed description of the entire guideline is beyond the scope of this article and the reader is directed to the published guideline in the Archives of Pathology & Laboratory Medicine, some of the guideline statements are of particular importance to the cytopathology community, and a brief overview is provided (Table 1).
Keeping in mind that there are existing recommendations from other professional medical societies pertaining to procedural aspects,5,6 the aim of the new guideline is to provide direction for collecting a thoracic small specimen that is adequate for downstream ancillary testing. With respect to cytology, specific guidelines are provided to the proceduralist pertaining to the choice of needle gauge (statement Nos. 2 and 6), number of passes (statement Nos. 4 and 7), utility of rapid on-site evaluation (ROSE) (statement Nos. 3, 4, 5, and 10), and optimal volume and triage of pleural effusion specimens (statement No. 11).
The multiple guideline statements pertaining to the use of ROSE, when available and clinically feasible, highlight the role of the cytologist during minimally invasive procedures, a role that can ensure adequate sampling of the targeted lesion as well as appropriate specimen triage for necessary ancillary studies. While overall the use of ROSE is recommended whenever possible, the expert panel acknowledges the potential complexity of different practice settings and clinical scenarios in which ROSE may not be needed or even practical, leaving room for clinical judgment to be used in determining the need for ROSE in all procedures.